Tensioner drives for belt retractors are known. In German laid-open document 21 21 101, there is described a seat belt for motor vehicles with a belt retractor and a tensioner drive. When a predetermined deceleration value is exceeded, a compressed gas cartridge is ignited and the compressed gas developed by the cartridge acts upon a turbine wheel. The compressed gas emerging from the compressed gas cartridge is fed to the turbine wheel via a single duct running essentially tangentially to the circumference of the turbine wheel. The turbine and the duct are accommodated in a common housing.
German patent specification 26 18 119 C2 describes a tensioner drive for a belt retractor in which the explosion pressure of a propellant charge acts upon a free jet turbine. A liquid transmitting the explosion pressure of the propellant charge is arranged between the propellant charge and the turbine in a container or coiled pipe. The liquid escapes through a single nozzle at the end of the container or coiled pipe and acts upon the self-contained turbine wheel. The turbine wheel and the belt reel are arranged on a common shaft.
The German laid-open document DE 43 19 273 A1 describes a belt retractor for vehicular seat belt systems, with a rotary belt tensioner drive engaging the belt reel. An up-gearing planetary gear drive is arranged between the belt tensioner drive and the belt reel.